Use options instead of hard-coded variables

Use options instead of hard-coded variables

* lisp/ox-beamer.el (org-beamer--format-frame,
  org-beamer--format-block, org-beamer-template): Use options instead
  of hard-coded variables.

* lisp/ox-man.el (org-man-inline-src-block, org-man-src-block,
  org-man-table, org-man-table-cell): Use options instead of
  hard-coded variables.

* lisp/ox-md.el (org-md-headline): Use options instead of hard-coded
  variables.

* lisp/ox-texinfo.el (org-texinfo-format-headline-function,
  org-texinfo-format-inlinetask-function): Change default value.
(org-texinfo--text-markup, org-texinfo--format-menu): Change signature
(org-texinfo--build-menu, org-texinfo-bold, org-texinfo-code,
org-texinfo-comment, org-texinfo-italic, org-texinfo-verbatim): Apply
signature change.

(org-texinfo-template, org-texinfo-clock, org-texinfo-drawer,
org-texinfo-link, org-texinfo-plain-list, org-texinfo-planning,
org-texinfo-table, org-texinfo-table-cell, org-texinfo-timestamp): Use
options instead of variable names.

(org-texinfo-format-headline-default-function,
org-texinfo-format-inlinetask-default-function): New functions.
(org-texinfo-headline, org-texinfo-inlinetask): Use new functions.